It is a comprehensive archive of Buddhist sutra and documents. Inside there is a kagami tenjō (mirror like ceiling), a mabaradaruki, flower shaped windows and all the implements typical of Zen architectural style. It was originally in Ōuchi Moriharu’s family temple, Kokuseiji. It was rebuilt in the actual place by Mōri Terumoto in 1602 (7th year of Keichō Era).